URDF gazebo element

#urdf   #gazebo  

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Table of Content

URDF gazebo element

The gazebo element is an extension to the URDF robot description format, used for simulation purposes in the Gazebo simulator.

Demo

Add gazebo tag to urdf file to control color in gazebo simulator

urdf

basic_gazebo.urdf

<?xml version='1.0' encoding='UTF-8'?>
<robot name='material_example'>
 <link name="world" />
    <joint name="world2link" type="fixed">
        <origin xyz="0.0 0.0 0.5" rpy="0.0 0.0 0.0"/>
        <parent link="world"/>
        <child link="base_link"/>
    </joint>
  <link name='base_link'>
    <inertial>
      <mass value='0.1' />
      <inertia ixx='0.01' ixy='0' ixz='0' iyy='0.01' iyz='0' izz='0.01' />
    </inertial>
    <visual>
      <geometry>
        <sphere radius="2"/>
      </geometry>
      <material name="Cyan">
        <color rgba="0 1.0 1.0 1.0" />
     </material>
    </visual>
  </link>
  <gazebo reference='base_link'>
    <material>Gazebo/Orange</material>
  </gazebo>
</robot>

launch

urdf_gazebo.launch.py

import os
from ament_index_python.packages import get_package_share_directory
from launch import LaunchDescription
from launch_ros.actions import Node

URDF = "basic_gazebo.urdf"
PACKAGE = "gazebo_tutorial_pkg"


def generate_launch_description():
    ld = LaunchDescription()

    pkg = get_package_share_directory(PACKAGE)
    urdf = os.path.join(pkg, "urdf", URDF)
    with open(urdf, "r", encoding="utf-8") as f:
        robot_description = f.read()

    robot_state_publisher = Node(
        package="robot_state_publisher",
        executable="robot_state_publisher",
        name="robot_state_publisher",
        output="screen",
        parameters=[{"robot_description": robot_description}]
    )

    ld.add_action(robot_state_publisher)
    return ld

rviz

launch include gazebo

urdf_gazebo_include.launch.py

import os

from ament_index_python.packages import get_package_share_directory
from launch import LaunchDescription
from launch.actions import IncludeLaunchDescription
from launch.launch_description_sources import PythonLaunchDescriptionSource
import xacro
from launch_ros.actions import Node

PACKAGE = "gazebo_tutorial_pkg"
URDF = "basic_gazebo.urdf"


def generate_launch_description():
    ld = LaunchDescription()

    pkg = get_package_share_directory(PACKAGE)
    gazebo_pkg = get_package_share_directory("gazebo_ros")

    gazebo = IncludeLaunchDescription(
        PythonLaunchDescriptionSource(
            [os.path.join(gazebo_pkg, "launch", "gazebo.launch.py")]
        ),
        launch_arguments={"verbose": "true"}.items(),
    )

    robot_description_path = os.path.join(pkg, "urdf", URDF)
    doc = xacro.parse(inp=None, filename=robot_description_path)
    xacro.process_doc(doc)

    robot_state_publisher = Node(
        package="robot_state_publisher",
        executable="robot_state_publisher",
        parameters=[{"robot_description": doc.toxml()}],
    )

    spawn_entity = Node(
        package="gazebo_ros",
        executable="spawn_entity.py",
        arguments=["-entity", "demo", "-topic", "robot_description", "-z", "0.0"],
        output="screen",
    )

    ld.add_action(gazebo)
    ld.add_action(robot_state_publisher)
    ld.add_action(spawn_entity)

    return ld